Diffusion pulp washer

ABSTRACT

A pulp washer and method wherein pulp and washing liquid are flowed in countercurrent relation along a given path, the path being interrupted transversely by a plurality of rotating arms which develop a plurality of high-dilution zones.

United States Patent [56] References Cited UNITED STATES PATENTS [72] inventor Frank B. K. Green 10835 S. W. Muirwood Drive, Portland, Oreg. 97225 m T 4 m m m m m f m mmw k w kk r aa 0%. kaa CSRLL 86367 25666 99999 HHHHH 0 23 1 0000339 28070 70878 83739 2333 $1 7 mm 9 1 9 g 5.J SSA 0. d N m L n wm .ua AFP ll] 25 224 [ll [54] DlFFUSION PULP WASHER Primary Examiner-William 1. Price Assistant Examiner-Philip R. C06

3 Claims, 5 Drawing Figs.

Attorney-Dawson, Tilton, Fallon & Lungmus ABSTRACT: A pulp washer and method wherein pulp and washing liquid are flowed in countercurrent relation along a given path, the path being interrupted transversely by a plurality of rotating arms which develop a plurality of high-dilution zones.

5 O8 3 .1 .l m4m nuw 91 1 O 3 5 dfl l 2 6/4 6 2082/ DD 3 w n "M m m5 u "3 m m m m3 3 n "2 u "2 m m m No 0 "O m2 m WA H m H W m m m m M L m f l 0 C M s m .m U I F l. l. 2 l 0 5 5 5 .l. .l. l.

PATENTED Am; 1 7 Ian DIFFUSION PULP WASHER BACKGROUND AND SUMMARY OF INVENTION Diffusion washing of pulp for removal of liquor is quite old. There has been a problem of achieving efficient washing, i.e., satisfactory removal of the liquor. Through the development of a plurality of thick waferlike sections by moving arms through he pulp mass, I am able to prevent short-circuiting of the wash liquor and provide more efficient washing.

DETAIL DESCRIPTION The invention is explained in conjunction with an illustrative embodiment in the accompanying drawing, in which:

FIG. 1 is an elevational view of a washer constructed accordingto the teachings of the invention, with certain of the piping shown in fragmentary form;

FIG. 2 is an enlarged fragmentary sectional view of the upper portion of the washer of FIG. 1;

FIG. 3 is an enlarged fragmentary sectional view of the lower portion of the washer seen in FIG. l;

FIG. 4 is an enlarged sectional view taken along the line 4-4 of FIG. 1; and j FIG. 5 is an enlarged fragmentary sectional view taken along the line 55 of FIG. 2.

In the illustration given, the numeral designates generally a vertically elongated casing which, as can be appreciated from a consideration of FIG. 4, is generally cylindrical in cross section. The lower end of the casing 10 is supported on suitable stanchions II which make it possible to conveniently couple means for withdrawing washed pulp as via the outlet pipe 12, and. means for supplying washing water as via the supply pic 13 (these are also similarly designated in FIG. 3). At the upper end, the casing is seen to be equipped with an inlet 14 for supplying pulp to be washed, as via the pipe 15. A black liquor outlet manifold 16 is also coupled to the top end of the casing 10 via a plurality of pipes 17. Interposed between the manifold 16 and the pipes 17 is a tee 18 which permits coupling the pipes 17 to a blowback line 19 for cleaning the screen 20. Suitable valves, as at 21 and 22, are interconnected with the tees 18.

The screen is seen to extend generally across the casing 10 (referring to FIG. 2) except for the central axial portion through which the unwashed pulp is introduced. Thus, the screen 20 has essentially an annular configuration as can be appreciated also from a consideration of FIG. 4.

Referring again to FIG. I, it is seen that the casing 10 is equipped with a vertically extending, axially positioned elongated shaft 23. The shaft 23 is suitably journaled within an upper baring generally designated 24 (see FIG. 2) and within a lower bearing generally designated 25 (see FIG. 3). A motor and speed-reducer unit, generally designated 26 (see FIG. 1), is coupled to the shaft 23 at the bottom extension thereof for rotating the same.

Referring to FIG. 3, it will be seen that the washing water flowing into the system through the inlet pipe 13 flows upwardly and substantially across the entire cross section of the casing 10 by virtue of being delivered trough plow arms'27 af fixed to the shaft adjacent the inner end of the casing 10. The shaft 23 is also equipped with nozzles, as at 28, which cooperate with the plow arm nozzles 29 enveloping the full cross'sectional pattern of washing liquid. Additionally, I find it advantageous to shield the spray nozzle as at 30.

Spaced below the plow arms 27 s the actual outlet port 31 for the washed pulp which exits through the line 12, the control thereof being effected by a ball valve 32.

The shaft 23 is seen to be equipped with a plurality of laterally extending arms 33 at points spaced along the length of the shaft 23 and which rotate therewith. Additionally, the shaft 23 at its extreme upper end is equipped with a wiper blade 34 which is seen to be equipped with an elongated bore as at 35 for the delivery of purging liquor against the screen 20. Black liquor for this purpose, is introduced through the upper end extension 36 of the shaft 23, and exits in the manner shown from the orifice 37 of the wiper blade arm. Each wiper blade arm 34 may be constructed of two portions as illustrated in FIG. 5, being integrated by a series of bolts 38 suitably countersunk.

The operation of the device, pulp is introduced through the conduit 15 into the central upper chamber 39 (see FIG. 2). By gravity, this, pulp flows downwardly in countercurrent relation to the upwardly flowing washing water which is introduced through the pipe 13. The series of arms 1149 mounted on the shaft form a series of high dilution areas in the mass of heavy consistency pulp moving down through the diffuser. These arms can be of any appropriate thickness. Especially advantageous is a thickness of the order of about 4 inches. With this width of arm and a suitable speed, the heavy consistency pulp will not fill the void behind the arms as fast as the wash liquor. As a consequence, each arm forms a high dilution area in its circumscribed path with high consistency pulp masses between the circumscribed paths. Consequently, the diffusion takes place trough several layers of heavy consistency pulp, somewhat compressed by virtue of thearms passing therethrough, between high dilution areas. This is especially effective in preventing any short circuiting of the wash liquid.

The wash liquid is spread over the full cross-sectional area of the casing or diffuser 10 via the provisions of the opposed sprays 28 and 29. Further, the spent liquor is removed over the full cross-sectional area of the diffuser via the screen 20 and he circumferentially spaced apart pipe 17.

I claim:

1. A pulp washer comprising a vertically elongated casing having an inlet and an outlet at both the top and bottom ends thereof, means for supplying pulp to be washed to the top inlet and washing liquid at the bottom inlet, means for removing liquor from the top outlet and washed pulp from said bottom outlet, an elongated shaft within said casing and extending substantially between said ends, means operably associated with said shaft for rotating the same, said shaft being equipped with a plurality of transversely extending arms spaced along the length thereof whereby rotation of said shaft develops zones of high dilution in said casing, said casing being equipped with a screen adjacent said top end, said shaft being equipped with a blade arm arranged to sweep the under side of said screen, and means for delivering liquor from said blade arm for purging said screen.

2. A pulp washer comprising a vertically elongated casing having an inlet and an outlet at both the top and bottom ends thereof, means for supplying pulp to be washed to the top inlet and washing liquid at the bottom inlet, means for removing liquor from the top outlet and washed pulp from said bottom outlet, an elongated shaft within said casing and extending substantially between said ends, means operably associated with said shaft for rotating the same, said shaft being equipped with a plurality of transversely extending arms spaced along the length thereof whereby rotation of said shaft develops zones of high dilution in said casing, said casing being equipped with a screen adjacent said top end, said shaft being equipped with a blade arm arranged to sweep the under side of said screen, and means for delivering liquor from said blade arm for purging said screen, said shaft being equipped with arm means adjacent said bottom end for delivering washing liquid into the pulp mass substantially across the full cross section of said casing.

3. A pulp washer comprising a vertically elongated casing having bearing means adjacent the top and bottom ends thereof, a shaft vertically extending in said casing and journaled in said bearing means, a plurality of laterally extending arms on said shaft extending laterally and positioned at points spaced along the shaft length, means coupled to said shaft for rotating the same, means for flowing pulp and washing liquor through said casing so that said arms develop zones of liquor concentration between zones of high consistency pulp, and screen means adjacent the upper end of said casing for restricting outflow of pulp, the shaft arms adjacent said screen means being equipped with fluid passage means for purging the under side of said screen means. 

2. A pulp washer comprising a vertically elongated casing having an inlet and an outlet at both the top and bottom ends thereof, means for supplying pulp to be washed to the top inlet and washing liquid at the bottom inlet, means for removing liquor from the top outlet and washed pulp from said bottom outlet, an elongated shaft within said casing and extending substantially between said ends, means operably associated with said shaft for rotating the same, said shaft being equipped with a plurality of transversely extending arms spaced along the length thereof whereby rotation of said shaft develops zones of high dilution in said casing, said casing being equipped with a screen Adjacent said top end, said shaft being equipped with a blade arm arranged to sweep the under side of said screen, and means for delivering liquor from said blade arm for purging said screen, said shaft being equipped with arm means adjacent said bottom end for delivering washing liquid into the pulp mass substantially across the full cross section of said casing.
 3. A pulp washer comprising a vertically elongated casing having bearing means adjacent the top and bottom ends thereof, a shaft vertically extending in said casing and journaled in said bearing means, a plurality of laterally extending arms on said shaft extending laterally and positioned at points spaced along the shaft length, means coupled to said shaft for rotating the same, means for flowing pulp and washing liquor through said casing so that said arms develop zones of liquor concentration between zones of high consistency pulp, and screen means adjacent the upper end of said casing for restricting outflow of pulp, the shaft arms adjacent said screen means being equipped with fluid passage means for purging the under side of said screen means. 